Kepler's First Law
Each planet moves in an ellipse (a flattened circle) with the sun at one focus (a point displaced from the centre).
Notice that the orbit isn't (quite) a circle, and that the sun isn't at its centre.
Each planet moves in an ellipse (a flattened circle) with the sun at one focus (a point displaced from the centre).
Notice that the orbit isn't (quite) a circle, and that the sun isn't at its centre.